> Should there be a watchdog which checks for a process which has run> realtime for a certain period and which then takes some action? Such as> descheduling it for a while, generating warnings, demoting its policy,> killing it etc?

Using the analogy of the OOM killer being called, this wouldn't be a badidea IMO - especially if it were configurable, and off by default. Thiscouldn't be done in a kernel thread (unless some new priority level werecreated for it), but I think the details can be worked out later.